X-ray crystal structure determinations will be carried out on compounds of biological interest, including a protein and a virus. The methods employed will emphasize computer-implemented Patterson searching, fast Gauss-Seidel refinement algorithms, and other recently introduced computational techniques. In the course of the research these techniques will be further developed, whenever possible. BIBLIOGRAPHIC REFERENCES: W.W. Smith, H.L. Crespi, B. Entsch, M.L. Ludwig and C.E. Nordman, Crystallographic Characterization of Flavodoxin from Anacystis nidulans. J. Mol. Biol. 94, 123 (1975). J. C. Hanson and C.E. Nordman, The Crystal and Molecular Structure of Corannulene, C20H10. Acta Cryst. B32. In press.